低碳贝氏体钢用烧结焊剂的研制及性能研究

Development and Properties Study of Sintered Flux Used for Low-carbon Bainitic Steel

基于低碳贝氏体钢的微观组织和性能研究分析,研制出以CaF_2-MgO-Al_2O_3-CaO为渣系的低碳贝氏体钢用高速埋弧焊烧结焊剂,匹配Mn-Ni-Mo-B合金系焊丝施焊,得到了一组性能优异的焊剂。结果显示:CaF_2加入量控制在23%以下,并增加TiO_2和SiFe含量来代替部分SiO_2时,得到的焊缝工艺性能优异,力学性能也能够满足使用要求。焊缝金属组织主要由针状铁素体、粒状贝氏体、以及少量的先共析铁素体和块状铁素体构成,较硬的粒状贝氏体弥散分布在较软的铁素体基体上,这种混合组织增加了裂纹扩展的路径,极大地增强了焊缝金属的韧性。而提高Al_2O_3和TiO_2的含量,同时将MnO的含量控制在6%左右,可以得到较多的针状铁素体,细化组织,使焊缝冲击韧性达到198 J。

Based on studying the microstructure and properties of low carbon bainitic steel, a high-speed submerged arc welding sintered flux with CaF2-MgO-Al2O3-CaO alkali fluoride slag system was developed, which was matched with Mn-Ni-Mo-B alloy system welding wire to weld, then, the weld flux with good properties was obtained. The results show that when the content of CaF2 is blew 23%, and increasing the contents of TiO2 and SiFe to replace a part of SiO2, the weld seam with good processing and required mechanical properties can be obtained. The microstructure of weld metal is mainly composed of acicular ferrite, granular bainite, a small amount of proeutectoid ferrite and polygo-nal ferrite. Harder granular bainite disperses in sorer ferrite matrix, which can increase the crack propagation path, therefore, the toughness of weld metal greatly enhances. What＇s more, when increasing the content of Al2O3 and TiO2, and controling the quantity of MnO at about 6%, more acicular ferrite can be gotten, which can refine the microstructure and make the impact toughness of weld reach 198J.